<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="bootstrap-3.4.1-dist/css/bootstrap.css">
</head>
<body>
    <button class="btn btn-primary">你好</button>
    <button class="btn btn-success">（成功）Success</button>
    <!-- Indicates caution should be taken with this action -->
    <button type="button" class="btn btn-warning">（警告）Warning</button>

    <!-- Indicates a dangerous or potentially negative action -->
    <button type="button" class="btn btn-danger">（危险）Danger</button>
    
</body>
</html>